Who says American politics is gridlocked? A tidal wave of politicians from both sides of the aisle who just a few years ago opposed same-sex marriage are now coming around to support it.

Elected officials who had been against allowing undocumented immigrants to become American citizens now want to "chart a path" for them.

Even those who were staunch gun advocates are now sounding more reasonable about background checks.

It's nice to think logic and reason are finally catching up with our elected representatives, but the real explanation for these changes of heart is more prosaic: public opinion.

Polls show greater support for marriage equality than ever before, with 58 percent of Americans in favor and 36 percent opposed, according to a recent Washington Post-ABC News survey. Several recent polls show that about 70 percent of Americans believe there should be a way for people in the United States illegally to remain in this country if they meet certain requirements. And polls show that about 90 percent of Americans support universal background checks of those purchasing a gun.

The exception is in the economic sphere, where public opinion seems beside the point.

Before January's fiscal cliff deal, for example, at least 60 percent of Americans expressed strong support for raising taxes on incomes over $250,000. But the deal locked in the Bush tax cut for everyone earning up to $400,000.

Polls also show Americans would prefer that taxes be raised to reduce the budget deficit rather than have future Medicare or Social Security benefits cut. Yet the president has offered to cut future benefits.

Legislative deals require compromise. But why is it that deals over economic policy almost always compromise away what a majority of Americans want?

Some 65 percent of Americans want to raise taxes on large corporations. But both parties are heading in precisely the opposite direction. According to a Rasmussen Reports poll, half of Americans favor a plan to break up Wall Street's 12 megabanks, which currently control 69 percent of the banking industry. Only 23 percent oppose such a plan. But our elected representatives won't even consider it.

Our politicians are sensitive to public opinion on equal-marriage rights, immigration and guns. Why are they tone-deaf to what most Americans want on the economy?

Because marriage rights, immigration and guns don't threaten big money in America. By contrast, any tinkering with taxes or regulations sets off alarm bells in our nation's finely appointed dining rooms and boardrooms -- alarm bells that, in turn, set off promises of (or threats to withhold) large wads of campaign cash in the next election.

When political scientists Benjamin Page and Larry Bartels recently surveyed Chicagoans with an average net worth of $14 million, they found their biggest concern was curbing budget deficits and government spending -- ranking these as priorities three times as often as they did unemployment.

And -- no surprise -- these wealthy individuals were also far less willing than other Americans to curb deficits by raising taxes on high-income people, and more willing to cut Social Security and Medicare. They also opposed initiatives most other Americans favor -- such as increasing spending on schools and raising the minimum wage above the poverty level.

The other thing distinguishing Page and Bartels' wealthy respondents from the rest of America was their political influence.

Two-thirds of them had contributed money (averaging $4,633) in the most recent presidential election. A fifth of them had even "bundled" contributions from others.

That money bought the kind of political access most Americans only dream of. About half of these wealthy people had recently initiated contact with a U.S. senator or representative, according to Page and Bartels -- and nearly half (44 percent) of those contacts concerned matters of relatively narrow economic self-interest rather than broader national concerns.

This is just the wealthy of one city -- Chicago. Multiply it across the entire United States and you begin to see the larger picture of whom our representatives are listening to, and why. Nor does the survey by Page and Bartels include the institutionalized wealth -- and economic clout -- of Wall Street and large corporations. Multiply the multiplier.

When it comes to issues such as same-sex marriage, undocumented immigrants and guns, our democracy seems to be working. It's far from perfect, of course. Certain special-interest groups like the NRA still have outsized influence.

But when it comes to economic issues that might affect the fates of large fortunes, American democracy isn't functioning at all. Big money talks, and it's speaking more loudly now than ever.